Pet Talent Transfer?

A couple days ago, I was seeking to hatch my forest beast to get an awesome pet. My pet had spell-proof, spell-defying, unicorn, and mana gift. I hatched with a pet that had spell-proof and fairy friend. I expected to retain all original talents, and gain fairy friend. I got the pet to adult yesterday, and wham out of nowhere, it gains Piercemonger (Adds 1 pierce card). Could someone please explain to me how on earth this happened?

A couple days ago, I was seeking to hatch my forest beast to get an awesome pet. My pet had spell-proof, spell-defying, unicorn, and mana gift. I hatched with a pet that had spell-proof and fairy friend. I expected to retain all original talents, and gain fairy friend. I got the pet to adult yesterday, and wham out of nowhere, it gains Piercemonger (Adds 1 pierce card). Could someone please explain to me how on earth this happened?

All talents given upon hatching are random; you should not assume that the original talents will re-manifest themselves in the hatchling.

A couple days ago, I was seeking to hatch my forest beast to get an awesome pet. My pet had spell-proof, spell-defying, unicorn, and mana gift. I hatched with a pet that had spell-proof and fairy friend. I expected to retain all original talents, and gain fairy friend. I got the pet to adult yesterday, and wham out of nowhere, it gains Piercemonger (Adds 1 pierce card). Could someone please explain to me how on earth this happened?